Base for shell case



' Feb, 18, 1958 R. P. THAYER 2,823,611

BASE FOR SHELL CASE Filed July 2, 1952 v INVENTOR. Ri ch'cmd 1 Thpyer y e (V V I J w n itttda Patent @r BASE FOR SHELL CASE Richard P. Thayer, Washington, D. C., assignor to the United States of America as represented by the Secretary of the Army Application duly 2, 1952, Serial No. 296,981

2 Claims. (Cl. 102-44) (Granted under Title 35, U. S. Code (1952), see. 266) The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment to me of any royalty thereon.

The present invention relates to a new and improved base for spiral wrapped shell cases and method for assembling the base and the spiral wrapped case. More particularly, the present invention relates to a novel and improved base for spiral wrapped shell cases and method for assembling the base and shell case, wherein the adaptor plate and the base plate are joined by external pressure thereby eliminating the use of threaded joints and of wrenches for tightening the threaded joint between the adaptor plate and the base plate as was done heretofore and which had the inherent disadvantage of being limited in strength as determined by the thread and the force which could be applied thereto.

It is accordingly an object of the present invention to provide a new and improved base for spiral wrapped shell cases which obviates the necessity for threaded parts and which permits ready assembly thereof.

It is another object of the present-invention to provide a base for spiral wrapped shell cases which consists of a base plate, an adapter plate and a seal which are assembled with the side walls of the spiral wrapped shell cases by the use of external pressure.

It is still another object of the present invention to provide a base for spiral wrapped shell cases wherein a minimum of machining is required to produce the various component parts thereof.

It is still a further object of the present invention to provide a complete seal between the various parts of the base and the case side wall by utilizing the pressure exerted by the resulting gases of the propellant against the adaptor plate.

It is another object of the present invention to provide an improved base for spiral wrapped shell cases which may be readily assembled in such a way as to maintain alignment between the case and the base.

It is a still further object of the present invention to provide a base plate and an adaptor plate which are fastened together by means of a rolled joint.

These and other objects and advantages of the present invention will be obvious from the following description when taken in connection with the accompanying drawing which shows for purposes of illustration only several of the preferred embodiments of the present invention, and wherein:

Figure 1 is a longitudinal, cross-sectional view of one embodiment of the base and shell case in their assembled condition;

Figure 2 is an exploded, cross-sectional view of the base shown in Figure 1;

Figure 3 is a longitudinal cross-sectional view of a modified embodiment of the base and shell case in their assembled condition;

Figure 4 is a front view of one half of the split ring used in the embodiment shown in Figure 3.

2,823,611 Patented Feb. 18, 1958 Referring now more particularly to the drawing wherein like reference numerals are used to designate like parts in the various figures thereof, reference numeral 1 designates the case wall of the spiral wrapped shell case, which utilizes two sheets of metal wrapped in opposite direction with the spiral of each advancing in the same axial direction. ,It is understood however that any other type of case maybe used with the base of the present invention. A base plate 2 is provided with a central bore 3 to receive adaptor plate 4. Base plate 2 comprises a countersunk portion 5 at the entrance of bore 3. Outer edge 6 of base 2 is chamfered. Base 2 also includes a reduced outside diameter portion '7 thereby forming shoulder 8. The right-side portion of base plate 2 which is in contact with the ends of side wall 1 is provided with a curved, cut-out portion 9 to accommodate the ends of case wall 1 of the shell case. A further relief portion 10 is provided to the left of outout portion 9. The adaptor plate 4 has a rearwardly extending reduced portion 11 of such diameter as to fit into bore 3 of base plate 2. Adaptor plate 4 further comprises a bore 12 having reamed portions 13 and 14 on both sides thereof .and constituting the primer hole as is well-known in the art. A relief portion 15 is provided in adaptor plate 4 opposite cut-out portion 10- of base plate 2. In order to provide the extra material necessary for the jointbetween base plate 2and adaptor plate 4, the latter comprisesa. circumferentially extending .bead 16 protruding from ;the deft-hand portion. of rearwardly extendingreducedportion1T1. A disc 17'having a central bore 18 slightly larger than rearwardly extending reduced portion 11 is inserted between ;base 2 and adaptor 4. Base plate 2 may be made fromplate or barstock, and requires finishing of. its surfaces prior to assembly asregards dimensions-only at bore 3, outside diameter surface'1-9, and reduced diametensurface'l, and

as regards orthogonality only at surfaces 20 of cut-out portion 9 and at shoulder surface 8. The adaptor plate 4 may be made of bar stock or forging, and requires finishing of its surfaces prior to assembly as regards dimension only at the outside diameter 21 of rearwardly extending reduced portion 11 and as regards orthogonality at surfaces 22 opposite surfaces 20 on base 2.

The assembly of the various parts takes place over an aligning fixture under any predetermined pressure. For example, adaptor plate 4 may be placed on a stationary, rounded fixture having a recess which serves to align the adaptor plate with respect to the longitudinal axis thereof. Next gasket or seal 17 is placed over rearwardly extending reduced portion 11 of adaptor plate 4. The stationary fixture may be made of smaller diametric dimension than the diametric dimension of the shell case 1 which may consequently be placed over it. Appropriate steps may be provided on the stationary fixture so that a sufiicient amount of case wall 1 will at all times be available to perform satisfactorily the crimping thereof. Base plate 2 is thereupon forced down in proper axial alignment with the shell case and adaptor plate 4, thereby forming the rolled joint 23. At the same time base plate 2, side wall 1, seal 17 and adaptor plate 4 form a more or less homogeneous mass at the point of mutual contacts depending only on the pressure used in the operation. It is of significance that joint 23 need only be a holding joint as it will not be subject to the resultant pressure caused by the ignited propellant. Although the joint is indicated as being formed by rolling, any other suitable method may be used, as for example, peening. The left-hand, rearward surface may be finished by machining after assembly of the base.

In order to strengthen the assembly against blow-outs which may occur as a result of pressure exerted by the gases produced by the ignited propellant on side Wall 1 which may leak around the outside diameter of adaptor plate 4, I propose the insertion of a split ring 24 one half of which is shown in Figure 4. Split ring 24 has an outside diametric dimension 25 substantially the same as the inside diameter of the shell case. The inside diameter 26 of split ring 24 is substantially the same as reduced diameter 27 of adaptor plate 4. Split ring 24 and adaptor plate 4 have complementary under-cut portions 28 so that they may be assembled as shown in Figure 3.

In the assembly of my modified base, the same fixtures may be used as are used with the base shown in Figure 1.

It is only necessary to place split ring 25 over adaptor plate 4 prior to inserting seal 17 over the rearwardly extending reduced portion 11 of adaptor plate 4. Seal 17 may be made of any suitable material such as, for instance, polyethylene.

The primer hole in adaptor plate 4 may be threaded or of any other configuration as may be required by the particular ammunition requirement. 7

Relief portions 10 and 15 in base plate 2 and adaptor plate 4 may be replaced by appropriate, circularly disposed bosses of such dimensions as will not interfere with the assembly of the base. Such bosses may be made by proper forging and may remain unfinished. Seal 17 may be varied accordingly by increasing inner bore 18 thereof so as to fit over the boss provided on adaptor plate 4 in the place of relief portion 15, i. e. the inner diameter of seal ring 17 is slightly larger than the outside diameter of the contemplated boss on adaptor plate 4.

While I have shown and described several preferred annular seat matingly engaging the curved rear end of said tubular member, said seat radially inwardly terminat ing in a fiat surface, an axial bore through said plate, a base recess between said bore and said fiat surface, a cylindrical adaptor of substantially the same diameter as the inside diameter of said tubular member, a rearwardly extended reduced portion integral with said adaptor extending through said axial bore and slideably engaging the wall of said bore, said adaptor having a fiat-face overlying the fiat surface of said base plate, and adaptor recess between said fiat face and said reduced portion, means to attach said adaptor to said base plate, a disk shaped sealing member concentric with said reduced portion and spaced therefrom, said sealing member being interposed between the curved end of said tubular member and the adjacent flat face of said adapter, the propellant gases acting on the exposed surface of said adaptor force said adaptor againstlsaid sealing disk, tubular member and the flat surface of said base to form a pressure seal under a force proportional to the pressure of the propellant gases, said adaptor and reduced portion having an axial bore therethrough to accommodate a primer.

2. The combination of claim 1, there being an under cut section in the outer peripheral portion of said fiat face, a split ring having one face engaging said under cut section and its other face engaging said sealing ring, said split ring being in tight peripheral engagement with the inner face of said tubular member, and having a raised bead in said one face to provide a smooth surface with said adapter for exposure to propulsion gases.

References Cited in the. file of this patent FOREIGN PATENTS Sweden -2 Aug. 8, 1944 

